The edge to edge aryl C—H···N dimer is a previously unrecognised intermolecular hydrogen bonded lattice packing motif; a search of the Cambridge Structural Database revealing that it is widespread amongst many classes of aromatic nitrogen-containing solids. This weak attractive interaction can be retained throughout crystal engineering studies as typified by the systematic modification of the diquinoline1into host-guest compounds formed by its dibromo derivative2.The latter is a molecule designed to form multimolecular inclusion compounds specifically with small polyhalocarbon guests.